Electron discharge device



Mach 3, 1953 J. ROTHSTEIN- ELECTRON DiSCHARGE DEVICE -Fi 1ed Aug. 14, 1950 .INVIENTOR.

JEROME ROTHSTEIN 7IZ AfTor-my Patented Mar. 3, 1953 UNITED STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE Jerome Rothstein, Belmar, N. J.

Application August 14, 1950, Serial No. 179,337

4 Claims. (01. 3154) (Granted under Title 35, U. S. Code (1952),

sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment of any royalty thereon.

The present invention relates to high frequency electron discharge devices of the velocity modulated or klystron type.

Prior known velocity modulated tubes are of two types, both of which employ cavities having an opening through which a beam of electrons is directed. In one type, two such cavities are employed, one to provide the velocity modulation and the succeeding cavity to act as a catcher. In another type, one cavity is employed and a reflector electrode is used to cause the electrons to return through the cavity opening. In both of these types, it is very diflicult to build cavities of the extremely small dimensions necessary for the higher frequencies and, in view of the sharp beam required, only a small cathode area can be used resulting in low power output and low efficiency.

It is therefore an object of this invention to provide a velocity modulated electron discharge device which an operate at higher frequencies.

Another object of the invention is to produce a velocity modulated electron discharge device which has higher efliciency and power output.

According to the invention, there is provided an ultra-high frequency electron discharge device comprising an evacuated envelope having a cylindrical cathode axially disposed therein. A plurality of cavity resonator are disposed in a circle about the cathode. Each of the cavities has a slot type opening which is parallel to the cathode and in a radial plane tangential to said cavity. A plurality of focusing electrodes are provided both for forming the electrons emitted from the cathode into a plurality of sheet-like beams, and for accelerating these radially towards said slot type openings. A repeller electrode circumferentially surrounds the cavity resonator to deflect each of the electron beams around at least one of the cavity resonators whereby the electrons, which are velocity modulated when passing past a slot due to the action of the cavity resonators, are deflected so as to arrive again at a cavity opening in the proper phase to impart energy thereto.

The invention, together with other objects that may hereinafter appear, will be better understood from the following description taken in connection with the accompanying drawing which is a diagrammatic transverse section of one embodiment of the invention.

In the drawing there is shown an evacuated envelope I which encloses the electron discharge device of this invention. A cathode 2 is axially positioned within this envelope. Cavity resonators 3 are disposed in a circle about the cathode. These cavities are tubular in shape but may have top and bottom caps. Each of the resonators has a longitudinal slot opening 4 disposed in a radial plane, which plane is tangential to the cavity. Electrodes 5 and 6 are provided to form sheet-like beams of electrons and to accelerate them past the opening in the cavity resonators. A repeller electrode 1 is positioned about the cavity resonators. An output coupling loop 8 is shown in one of the cavities.

In operation, the electrons emitted from the cathode are formed into sheet-like beams of electrons by means of the beam forming electrodes 5 and 6. The potentials of these electrodes are adjustable. Since these electrode are at positive potentials with respect to the cathode, the electrons are accelerated past the cavity opening and shock excite the cavity oscillator. As in conventional klystrons or in magnetrons there will be a difference in potential across the slot which will result in an acceleration or retardation of the electrons as they move past the slot. The potential of the repeller electrode is negative with respect to the cathode and the repeller is so positioned and formed as to cause the electrons to trace a curved path about at least one of the other cavity oscillators. As in conventional klystrons, the time of transit may be controlled by adjusting the repeller voltage so that the electrons will be bunched when they arrive at the opening in this other cavity and the time of arrival or phase will be such as to impart energy thereto. This will increase the intensity of oscillation of the cavity causing the electron beam, which is crossing it in the opposite direction, to undergo greater acceleration or deacceleration producing a greater bunching efiect at the third cavity. Thus it will be seen that there will be a progressive building up of the amplitude of the oscillations. As in conventional klystrons, the electrons may be made to go through more than one cycle before being collected by the beam forming electrode or the cavity oscillator walls, which may be operated at a slightly positive direct-current potential.

It will also be seen that the structure disclosed has inherently higher power possibilities because of the use of the entire emitting surface of the cathode, the use of sheets of electrons instead of narrowly focused beams and greater plate dissipation since the whole cavity helps to dissipate the heat. The type of cavity used, which is similar to the type employed in the magnetron except for the positioning of the opening in the cavity, permits of higher frequencies due to the fact that small cavities of this nature are much easier to construct than the cavities and the grids of the conventional klystrons.

As in the magnetron, the mode of operation can be stabilized by strapping and tuned by using the Crown of Thorns type of tuning.

While there has been described what is at present considered the preferred embodiment of the invention, it is obvious to those skilled in the art that variou changes and modifications may be made therein Without departing from the invention, and, it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. An ultra-high frequency electron discharge device comprising an evacuated envelope, a cylindrical cathode disposed within said envelope, a plurality of cavity resonators circumferentially and coaxially disposed about said cathode, each of said cavity resonators having an opening in a radial plane, a plurality of focusing electrodes 'circumferentially surrounding said cathode for forming a plurality of radial beams of electrons, reflecting means circumferentially surrounding said plurality of cavity resonators for deflecting each of said beams around at least one of said cavity resonators, potential means connected to all the elements for applying and adjusting the potentials on each of the elements of said discharge device whereby the electrons are velocity modulated and deflected to traverse a cavity opening in the proper phase to impart energy thereto.

2. An ultra-high frequency electron discharge device comprising an evacuated envelope, a cylindrical cathode axially disposed within said envelope, a plurality of cavity resonators circumferentially and coaxially disposed about said cathode, each of said cavity resonators having an opening disposed along a radius of said cathode, a plurality of focusing electrodes circumferentially surrounding said cathode for forming a plurality of sheet-like beams of electrons, a reflecting electrode circumferentially surrounding 4 said plurality of cavity resonators for deflecting said beams around said cavity resonators, and potential means connected to all the elements for applying and adjusting the potentials on each of said electrodes whereby the electrons of each of said beams are velocity modulated and deflected to arrive at a cavity opening in the proper phase to impart energy thereto.

3. An ultra-high frequency electron discharge device comprising an evacuated envelope, a cylindrical cathode centrally disposed Within said envelope, a plurality of cavity resonators disposed about said cathode, each of said resonators having a slot opening tangentially disposed along a radius of said cathode, means circumferentially surrounding said cathode for forming a plurality of sheet-like beams of electrons and directing each of said beams past an opening in a correspond- I ing one of said cavity resonators and means encompassing said resonators for causing each of said beams to pass at least one other of said slot openings.

4. An ultra-high frequency electron discharge device comprising an evacuated envelope, a cylindrical cathode centrally disposed within said envelope, a plurality of cavity resonators disposed in a circle about said cathode, each of said cavity resonators having a slot opening tangentially disposed along a radius of said cathode, means circumferentially surrounding said cathode for forming a corresponding plurality of sheet-like beams of electrons and directing each of said beams past an opening in one of said cavities, and means encompassing said resonators for causing each of said beams to pass at least one other of said slot openings.

JEROME RO'II-ISTEIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,190,668 Llewellyn Feb. 20, 1940 2,459,805 Fremlin Jan. 25, 1949 2,584,323 Berterottiere Feb. 5, 1952 FOREIGN PATENTS Number Country Date 577,037 Great Britain May 2, 1946 

